Internal-combustion engine



Feb. 12, 1929. 1,701,599

' L. M. WOOLSON INTERNAL COMBUS TION ENGINE Filed Oct. 10, 1924 3144mmfoe Z5 LiOILGZ MTVbolso'lL Patented Feb. 12, 1929. .QUNITED STATES mum.

PATENT OFFICE.

1T. WOOLSON, 013 DETROIT, MICHIGAN, ASSIGNOR TO PACKARD MOTOR GARCOMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN.

INTERNAL-COMBUSTION ENGINE.

Application filed October 10, 1924. Serial No. 742,776.

. This invention relates to internal combustion enginesand moreparticularly to valve mechanisms.

, The valve mechanism of an internal combustion engine usually comprisespoppet valves and a camshaft together with means such as tappetmechanisms for operating the on its seat. If this clearance is notprovided the valve will ride and consequently will not close tightlywith the result that the port will leak and. the valve be burned. Thehorsepower of the engine will also fall off so due to the fact that fullcompression cannot be obtained. p I

If the tappet mechanism is adjusted for the proper clearance when theengine is cold, this clearance will sometimes be taken up entirely byelongation of the valve stem when the engine gets hot. This necessitatesa greater amount of clearance being provided when the motor is cdld withthe result that this greater clearance causes a clicking action and thusmakes the engine disagreeabl noisy. Various means have been provided orautomatically taking up this clearance or damping its action to mitigatethe noise difliculty but none of these have proven entirely satisfactorydue to the complication involved and the inoperativeness of some ofthem.

One of the objects of the present invention is to provide an automaticmeans for taking up the clearance between the valve and its.

operating mechanism while at the same time providing for a firm closureor seating of the valve.

Another object of the invention is to provide a clearance take-upmechanism that is retracted during each opening and closing cycle of thevalve, so that the valve may be insured'of a firm seating.

. Another object of the invention is to provide an automatic take-up fora valve mechanism together with means for retracting the take-up meansimmediately before the valve is opened, thus insuring a firm seatingofthe valve when it closes.

Another object of the invention is to provide an automatic take-up meansfor a valve mechanism operating through lateral movement of the valvestem.

Another object of the invention is to provide an automatic take-up meansfor a valve mechanism operating with a limited movement in combinationwith adjusting means for normally positioning the parts.

Other objects of the invention will appear from the followingdescription taken in connection with the drawings, which form a part ofthis specification, and in which:

Fig. 1 is a transverse section through an internal combustion engineembodying the invention;

Fig. 2 is a somewhat enlarged similar section showing part only. of themechanism illustrated in Fig. 1, with the take-up mechanism in section,and

Fig. 3 is a section on the line 3-3 of Fig. 2.

Referring to the drawings, 10 represents an engine cylinder mounted onthe crankcase 11 and havin a piston 12 and a connecting rod 13. Thecylinder is also pro-- vided with a cylinder port 14 which may be eitheran inlet or an exhaust port, and this port is closed by a poppet valve15 of usual construction. The valve is movable in a guide 16 secured inthe cylinder casting and a spring 17 yieldingly retains the valve inclosed position as shown in the drawing.

The valve stem is indicated at 18 and it is shown as'having someclearance between it and the interior of the guide 16' as indicated at18'. In exhaust valves this clearance is frequently as much as six oreight thousandths of an inch so that the valve will not stick when itbecome hot. This clearance also allows for slight lateral movement ofthe valve in the guide as will hereinafter more full appear. 95

The valve stem 18 is operated upon to open the valve by a tappetmechanism indicated generally at 19. This mechanism comprises a uide 20mounted in the crankcase 11, a.

sli ing tappet 21 mounted in the guide, a

tappet bolt 22 threaded into the tappet for longitudinal adjustmenttherein, and a nut 23 for locking the bolt 22 in adjusted .position. Acap 24 is also provided to prevent oil from working up around the tappet21. m

In the crankcase 11 is mounted a camshaft 25 which is operatedin theusual way from the motor crankshaft, not shown in the drawing. There isa cam 26 for each of the valves of the engine, which cams are posiuptioned to open and close the valves on the usual four-stroke cycle.

Arranged between the camshaft 25 and the tappet mechanism 19 is a rockerarm 27 which is pivoted at 28 to a bearing member 29 of the crankcase.This rocker arm bears against the camshaft at the point 30 and at itsouter end it bears against the tappet 21 as at 31. From this it will beseen that as the cam 26 passes under the arm 27 the latter is rockedand-the tappet 21 is lifted or moved upwardly against the stem 18 of thepoppet valve 15, thus raising the valve from its seat. As the cam 26rides out from under the arm 27 the spring 17 returns the valve 15 toits seat. v

Mounted upon or formed as a part of the tappet mechanism 19 is thedevice for taking up the clearance between the valve operating means andthe valve. As shown herein, this comprises an enlarged head 32 on thebolt 22, and this head has an inclined upper surface 33 with side wallsor flanges 34 on each side thereof. It has been found that this inclinedsurface should be about. eleven degrees from a horizontal plane when thevalve mechanism is arranged vertically as shown in the drawings, thisposition of the inclined surface being indicated at 35 in Fig. 1.

A contact piece or wedge 36 is positioned on the head 32 between theflanges 34: so that this wedge is arranged between the upper end of thebolt 22 and the stem 18 of the valve. The lower face of the wedge isinclined to fit the surface 33 as shown and its upper face is horizontaland arranged to bear against the lower end of the valve stem 18. Inorder to increase the friction between the upper surface of the wedgeand the lower end of the valve stem the wedge is preferably roughened asat 37.

The wedge 36 is formed with down turned flanges 38 and 39 at itsrespective ends and the distance between these flanges is a little morethan the width of the head 32 so that the wedge 36 has a limited slidingmovement in two directions on the inclined surface 33. A spring 40.preferably seated in a recess 41 in the head 32, as shown in Fig. 2,yieldin ly presses against the flange 38 so that the we ge is constantlyurged towards the right in Figs. 1 and 2 of the drawing thus takin upany clearance that may exist between t e u per end of the bolt 22 andthe lower end 0 the valve stem 18, within the limits of movement of thewedge. I

Since the take-up device is mounted on the head 32 of the bolt 22 itwill be seen that the device may be adjusted vertically orlongitudinally of the valve stem 18 by simply turning the bolt 22relative to the tappet 21, and it ma be locked in adjusted position bythe 100i nut 23. In adjusting the mechanism, therefore, with the valve15 seated, the tappet 21 and bolt 22 will be relatively adjustedupwardly against the valve stem until the wedge 36 is substantially inmid-position betweenits limits of movement and with its upper face incontact with thelower end of the valve stem. After such adjustment, whenthe engine is operated the cam 26 will move the tappet 21 upwardly andthe initial movement thereof, due to the strong tension of the valvespring 17, will cause the wedge 36 to slide down the incline 33 or movelaterally relative to the tappet mechanism, and this will cause alateral movement of the lower end of the valve stem 18, this beingbecause of the slight clearance between the valve and its guide, thevalve stem being carried laterally with the wedge 36. This slightcocking of the valve will make it easier to open the valve, if it is anexhaust valve, because this cocking of the valve will slightly relievethe pressure in the engine cylinder and consequently relieve thepressure against the head of the poppet valve 15. Even though theclearance between the valve stem and its guide is not suflicient to thuscrack the valve open, yet it will always be enough to permit slidingaction of the wedge 36 for thus retracting the wedge from its fulltakeup position.

In the further operation of the engine, as the cam 26 passes from underthe arm 27 and thus permits the tappet mechanism 19 to descend, thevalve spring 17 will close the valve and, because of the retractedposition of the wedge 36 the valve will firmly seat. After the valve hasbecome fully seated and the cam 26' is entirely out from under the arm27, the spring 40 will operate to move the wedge 36 towards the rightand thus take up the clearance between the tappet mechanism and thevalve stem 18. Again as the valve is lift-- ed this retraction of thewedge 36 again takes place and as the valve closes the take-up action ofthe wedge is repeated, and so on for each opening and closing operationof the valve.

The vertical adjustment of the take-up device as described above isusually required only after the engine valves have been ground or the'valves have otherwise been changed relative to the tappet mechanism. Inorder to make the adjustment more readily, the wedge 36 is formed with atransverse hole 36 therein and the flanges 34 have corresponding holes34', and these holes are relatively arranged so that when they arealigned the wedge 36 will be in its midposition. Thus, when the take-updevice is to be adjusted, a pin may be inserted in the aligned holes oropenings 36', 34', which will thereby hold the wedge in itsmid-position, and the bolt 22 will then be adjusted relatively to thetappet 21 until the upper surface of the wedge 36 is in contact with thelower end of the seated valve. The pin will then be removed a d theadjustment will be complete.

While I have herein described in some deguide,

tail a specific embodiment of my invention,

which I deem to be new and advantageous and may specifically claim, I donot desire it to be understood that my invention is limited to the exactdetails of the construction, as it will be apparent that changes may bemade therein without departing from the spirit or scope of my invention.

' said stem being slightly smaller in diameter than the interior of theguide whereby said valve is adapated to move therein, means foroperating the valve having a clearance with respect to said valve, andmeans adapted to move within limits defined by the clearance betweensaid valve stem and guide, for automatically taking up the clearancebetween said operating means and the valve stem.

2. In an engine, in combination, a valve guide, a valve having a stemtherein with clearance between the stem and guide, and means foroperating the valve, including an automatic take-u device adapted tomove the valve stem .bot longitudinally and transverse] in its guide.

3. n an engine, in combination, a poppet valve adapted to movetransversely and longitudinally, a tappet for opening the valve, and adevice between the tappet and the valve for causing transverse movementof the valve as the tappet starts to lift the valve.

4. In an engine, in combination, a valve avalve having a stem thereinwith clearance between the stem and guide, and means for operating thevalve including an automatic take-up device adapted to move the valvestem transversely in its guide.

5. In an engine, in combination, a valve uide, a valve having a stemtherein with c earance between the stem and guide, means for operatingthe valve, and an automatic take-up device between said means and thevalve stem ada ted to move the valve stem transversely in its guide.

6. In'an engine, in combination, a valve guide, a valve having a stemtherein with clearance between the stem and guide, means for operatingthe valve, and an automatic take-up device between said means and thevalve stem comprisin a tappet, a bolt adjustabl mounted in sai tappetand having an inc ined surface, a wedge device cooperating with theinclined surface on the bolt adapted to move in two directions, andmeans for yieldingly moving the wedge device in one directlon.

7. In an engine, in combination, a valve guide, a valve having a stemtherein with clearance between the stem and guide, means for operatingthe'valve, and an automatic take-up device between said means and thevalve stem comprising a tappet, a bolt adjustably mounted in said tappetand having an inclined surface, a wedge-device cooperating with theinclined surface on the bolt having limited movement in two directionsand adapted to move the valve stem transversely in its guide, and meansfor ieldingly moving the wedge device in one irection.

8. In an engine, in combination, a Valve having a stem, means foropening thevalve,

and a take-up device between the valve stem.

and said opening means for causing a transverse movement of the valvestem.

9. A clearance take-up device comprising a tappet, a bolt adjustablymounted in said tappet and having an inclined surface, a wedge devicecooperating with the inclined surface on the bolt and having means limiting movement of said device in twodirections, and a spring operating toyieldingly move said wedge device in one direction.

In testimony whereof I aflix my signature.

LIONEL M. WOOLSON.

